Active Layer Monitoring Stations (ALMSs) are designed to measure soil temperature, soil moisture (as volumetric water content; VWC), and specific conductance (as electrical conductivity; EC) of active layer soils at various depths. At each station, sensors are deployed at 4-5 sites (A-E) in a 1-dimensional vertical orientation. For example, at Green Creek, sites A and B are located near the thalweg, site C is located at the wetted margin, and sites D and E are located in distal soils further from the channel of the stream.

Decagon 5TE sensors are used to measure soil temperature, volumetric water content, and pore water electrical conductivity at specific depths in the soil profile. Each 5TE sensor is wired into a Campbell Scientific AM16/32B 16-Channel Relay Multiplexer, which is connected to a CR1000 Measurement and Control Datalogger. In very dry soils, specific conductance measurements may be unreliable. Furthermore, specific conductance observations in frozen soils are also unreliable. To interpret these data, we suggest looking at coincidentally observed temperature and soil moisture observations. Pore water specific electrical conductivity is measured with an accuracy of 10% and resolution of 0.01 dS/m. Notably, VWC is not calibrated for each sensor so relative changes should only be considered and care should be taken when comparing values between sensors.

K-Type, Duplex Insulated Omega® Thermocouple Wire was cut and insulated at one end to measure soil temperature at several additional depths within each site at each station to complement temperature data recorded by the 5TE sensors. Thermocouples are wired into a Campbell Scientific AM25T 25-Channel Solid-State Thermocouple Multiplexer, connected to a CR1000 Datalogger. Thermocouples measure temperature within a range of -250 to +250°C, at an accuracy of 2% below freezing and 0.75% above freezing, and a precision of 0.001 °C.